The present invention relates to a wireless article and, in particular, to a wireless article including an antenna.
Wireless articles, such as tags, identification badges, smart cards and the like, are in wireless communication with a base unit or reader via a radio-frequency (RF) communication link. RF transmissions transmitted by the base unit may be received by an antenna on the wireless article or RF transmissions transmitted by the wireless article by an antenna thereon may be received by the base unit. Or RF transmissions by each of the wireless article and the base unit may be received by the other one thereof.
In each case, the RF signals either received or transmitted by the wireless article are received or transmitted by an antenna thereon. Because wireless articles are usually desired to be small in size, the antenna thereon must also be small in size. For a loop-type antenna, the sensitivity of the antenna to small amplitude RF signals and the amplitude of the RF signals transmitted by the antenna are a direct function of the area enclosed by the antenna loop and the number of turns of the conductor forming the loop. For a small tag or badge, the size thereof limits the area that an antenna loop can enclose, thereby limiting the RF performance of the antenna. Typically, RF identification tags operate in the frequency range of 100 KHz to 3 GHz, or higher.
Wireless articles, such as RF tags, are often used for purposes of security or other purposes where it is desirable that a rugged wireless article be permanently attached to an object and that any attempt to remove, alter or otherwise tamper with the wireless article, or attach the wireless article to a substitute object, be evident. The need for such security is particularly acute when the value of the objects to be controlled or inventoried is high. Conventional RF tags have been ruggedized and/or fortified so as to be physically resistant to tampering or to survive in hostile environments, such as laundering or industrial processing, or in repeated usage, however, the conventional approach has typically been to add physical reinforcement, thereby adding further undesirable complexity and cost to the conventional tag.
Accordingly, there is a need for a wireless article having a structure that readily evidences and/or resists tampering and yet is relatively simple and relatively inexpensive to make.
To this end, the tamper-resistant article of the present invention comprises a substrate including at least one layer of a strong dielectric adhesive having an exposed surface adapted for attaching said substrate to an object. A pattern of electrically-conductive material including an elongated electrical conductor is on one surface of the substrate and has at least one electrical contact. At least one electronic device is attached to the substrate by a strong adhesive and has at least one contact electrically connected to the contact of the pattern of electrically-conductive adhesive, whereby at least one of the strong dielectric adhesive of the substrate and the strong adhesive attaching the electronic device render the article resistant to tampering.
According to another aspect of the invention, a tamper-destruct article comprises a substrate including at least one layer of a dielectric adhesive having an exposed surface adapted for attaching the substrate to an object. A pattern of electrically-conductive material including an elongated electrical conductor is on one surface of the substrate and has at least one electrical contact. At least one electronic device is attached to the substrate by an adhesive and has at least one contact electrically connected to the contact of the pattern of electrically-conductive adhesive, wherein at least one of the pattern of electrically conductive material and the electrical connection of the contact of the electronic device to the substrate includes at least one frangible region.